JP2011029215A - Cylindrical bond magnet and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bond magnet for improving strength and magnetic force. <P>SOLUTION: In the cylindrical bond magnet made of magnetic powder and resin, the cylindrical bond magnet is a single forming body, at least four N and S poles are alternately subjected to multi-pole magnetization in an axial direction, and an inner diameter of the cylindrical bond magnet is within a range of 10 to 65%, thus obtaining a magnet having improved strength without inserting into a pipe and easily manufacturing the bond magnet having improved magnetic force by such a magnet. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a cylindrical bonded magnet in which N poles and S poles are alternately multipolar magnetized in the axial direction.

  In recent years, columnar magnets and cylindrical magnets in which a plurality of permanent magnets are arranged so that the same kind of magnetic poles face each other are used in various fields. For example, the magnet disclosed in Patent Document 1 is used in a foreign matter removing device for removing iron powder or the like from food, or a stator or a mover of a linear motor. Such columnar and cylindrical magnets have N and S poles alternately formed radially in the axial direction on the outer peripheral surface. For example, in the case of the N pole, the magnetic force lines generated from these extend radially from the N pole in a direction orthogonal to the axial direction, and draw a large arc to the S pole adjacent to the N pole. As a result, many magnetic fields can be effectively formed on the outer peripheral surface of the columnar or cylindrical magnet. Thereby, in the case of a foreign matter removing apparatus, the foreign matter collecting ability can be increased, and in the case of a linear motor or a vibration motor, a strong driving force can be obtained. Hereinafter, such a magnet is referred to as a columnar or cylindrical alternating multipolar magnet.

JP 2003-303714 A

  When obtaining the above-mentioned alternating multipole magnet, it was necessary to bond the cylindrical and cylindrical magnet pieces magnetized in the axial direction so that the same poles face each other while using an adhesive or the like. . In these methods, when assembling the magnet, the same kind of magnetic poles must be opposed to each other, and since they are subjected to a large repulsive force, they are very dangerous and workability is poor, and until the adhesive is solidified, a jig is used. There was a problem that productivity was low because it was necessary to fix the magnet. In addition, when an adhesive is used, there is a problem that the size of the adhesive surface varies depending on the amount of the adhesive used, the manner of application, and the like. Such a problem becomes more serious because the number of bonded portions increases as an alternate multipolar magnet having a larger number of magnetic poles is manufactured. Thus, when manufacturing the final columnar and cylindrical alternating multipolar magnets, there is a problem that it is very difficult to make the overall length a desired dimension.

  In addition, alternating multipole magnets obtained by assembling conventional cylindrical magnets and pieces of cylindrical magnets one by one using an adhesive or the like are used for applications such as linear motor stators and foreign substance removal devices, for example. In addition, in order to give strength to itself, it is inserted into a non-magnetic pipe such as stainless steel. However, when inserted into a non-magnetic pipe, there is a problem that the available side magnetic force, which is the main feature of the alternating multipolar magnet, decreases with the thickness of the pipe. In addition, the alternating multi-pole magnet obtained as an integrated molded body is originally integrated, so it can be used without being inserted into a pipe, but it is incorporated into a main body device such as a foreign substance removing device or a linear motor. In this case, there is a problem that the strength is insufficient as it is.

  This invention is made | formed in view of such a condition, The main objective is to provide the magnet which improved the intensity | strength of the magnet, without inserting in a pipe, and its manufacturing method.

  In order to achieve the above object, the cylindrical bonded magnet according to the first aspect of the present invention is a cylindrical bonded magnet formed of magnetic powder and resin and having a hollow through hole opened therein. The cylindrical bonded magnet is a molded body that is integrally formed, and has multiple N poles and S poles that are alternately multipolar magnetized in the axial direction of the through hole. The inner diameter can be in the range of 10% to 65% of the outer diameter. Thereby, unlike the bonded magnet formed by joining a plurality of pieces, an integrally molded bonded magnet can be obtained, and sufficient magnetic force and strength can be provided.

  Further, the cylindrical bonded magnet according to the second side surface can further include a core rod inserted into the through hole and having an outer diameter substantially the same as the inner diameter. Thereby, even if it does not insert a cylindrical bond magnet in a pipe etc., sufficient intensity can be provided by letting a core go through a through-hole.

  Furthermore, in the cylindrical bonded magnet according to the third aspect, the magnetic powder constituting the cylindrical bonded magnet can be an anisotropic rare earth alloy powder.

  Furthermore, the manufacturing method of the cylindrical bonded magnet according to the fourth aspect includes a step of kneading magnetic powder and resin to obtain a compound, and forming the compound into a cylindrical bonded magnet in an environment where an orientation magnetic field is applied. A method for producing a cylindrical bonded magnet including a step, wherein the orientation magnetic field is formed by an orientation magnet in which a plurality of permanent magnets are joined so that the same kind of magnetic poles face each other, It can arrange | position so that the said cylindrical bond magnet may be enclosed. Thereby, unlike the bonded magnet formed by joining a plurality of pieces, an integrally molded bonded magnet can be obtained, and sufficient magnetic force and strength can be provided.

  According to the present invention, a magnet with improved magnet strength can be obtained without being inserted into a pipe, and a magnet with improved magnetic force can be easily manufactured with such a magnet.

It is a schematic cross section which shows the metal mold | die for magnet molding. It is a perspective view which shows the magnet for orientation for orienting the magnet in FIG. It is a schematic cross section which shows the metal mold | die for magnet formation which has arrange | positioned the center pin. It is a perspective view of a cylindrical bond magnet. It is a perspective view which shows the state which inserted the core iron into the cylindrical bond magnet of FIG. It is a schematic cross section which shows the magnetic force line | wire which generate | occur | produces with the permanent magnet for orientation in the metal mold | die of FIG. It is a graph which shows the side surface maximum surface magnetic flux density of a bond magnet. It is a perspective view which shows the magnetizing coil used for a magnetization process.

  The best mode for carrying out the present invention will be described below with reference to the drawings. However, the form shown below illustrates the cylindrical bonded magnet and its manufacturing method for embodying the technical idea of the present invention, and the present invention limits the cylindrical bonded magnet and its manufacturing method to the following. Not what you want.

  Further, the present specification by no means specifies the members shown in the claims to the members of the embodiments. The dimensions, materials, shapes, relative arrangements, and the like of the components described in the embodiments are not intended to limit the scope of the present invention only to the description unless otherwise specified. It is just an example. Note that the size, positional relationship, and the like of the members shown in each drawing may be exaggerated for clarity of explanation. Further, in the following description, the same name and reference sign indicate the same or the same members, and detailed description will be omitted as appropriate. Furthermore, each element constituting the present invention may be configured such that a plurality of elements are constituted by the same member and the plurality of elements are shared by one member, and conversely, the function of one member is constituted by a plurality of members. It can also be realized by sharing.

  FIG. 1 is a schematic sectional view of a mold for producing a cylindrical bonded magnet, and FIG. 2 is a schematic perspective view of a permanent magnet for orientation arranged in the mold of FIG. Each is shown. In FIG. 2, the ejector pins and the partition walls of the mold shown in FIG. 1 are not shown for simplicity of explanation.

  The manufacturing method of the cylindrical bonded magnet is not the method of assembling the magnet pieces one by one as in the conventional method, but a single molded body is generated by one molding, and N and S poles are generated alternately in the axial direction. This is a manufacturing method. According to this manufacturing method, as shown in the mold internal cross-sectional view of FIG. 1, a compound made of anisotropic magnetic powder and resin is molded inside a cavity surrounded by a permanent magnet for orientation. The magnetic powder in the compound is oriented to obtain a cylindrical alternating multipolar magnet in which N poles and S poles are alternately generated in the longitudinal direction. Since the permanent magnets for orientation are arranged so that the same kind of magnetic poles face each other inside the mold, a magnetic field is generated in the cavity to sufficiently orient the anisotropic magnetic powder. . Since these magnets are excellent in magnetic properties, a single alternating multipolar magnet can be produced by one molding, so that productivity and dimensionality are extremely excellent.

  Hereinafter, the manufacturing method of a cylindrical bonded magnet is demonstrated in detail. In FIG. 1, the anisotropic magnetic powder in the molten compound injected from the gate 106 is filled into the cavity 105 and formed into a cylindrical shape. The outer shape of the bonded magnet to be molded is not limited to a cylindrical shape, and may be a shape such as an ellipse, a triangle, a square, or other polygons in addition to a circular cross section.

  The molding method is not particularly limited, and for example, extrusion molding, compression molding, or injection molding can be applied. In view of productivity and ease of installation of orientation equipment, it is particularly preferable to form by injection molding.

  Further, the axis of easy magnetization is aligned by a permanent magnet for orientation until the molten compound is solidified inside the mold. The molded bond magnet is sufficiently solidified in the mold and then ejected by the ejector pin 103.

  Here, the permanent magnets 101 and 102 for orientation are arranged so that the same type of magnetic poles of the small magnet 101a (102a) and the small magnet 101b (102b) having a U-shaped cross section face each other as shown in FIG. Yes. Further, the permanent magnets 101 and 102 for orientation are arranged so that the U-shapes face each other so as to form the cavity 105. FIG. 6 shows the state of magnetic lines of force obtained inside the mold cavity 105 by the orientation permanent magnets 101 and 102 having such an arrangement. For example, in the case of the facing surfaces of N poles, the lines of magnetic force are repelled on the facing surfaces to generate a strong magnetic field toward the inside of the cavity. Thereafter, the lines of magnetic force continue to the surfaces where the adjacent S poles face each other. Along the magnetic field lines, the anisotropic magnetic powder in the compound is oriented, so that a radial magnetic pole having a strong magnetic force appears on the side surface of the molded product. By the way, this magnetic field line is stronger as it is closer to the outer periphery of the cavity, and is weaker as it is closer to the center. That is, it is the outer side surface portion of the molded magnet that provides a high magnetic force.

  Here, the material used for the orientation permanent magnet is preferably one having a residual magnetic flux density Br of 1 T or more, and for example, a NdFeB sintered magnet can be used. When a magnet having a large magnetic force is used, the magnetic force generated inside the cavity is increased, and the magnetic force of the bonded magnet is also increased.

  The alternating multipole magnet obtained by injection molding can be used as it is because it is oriented and magnetized in the mold, but a magnetizing step may be performed after molding. By magnetizing, the magnetic force of the bond magnet can be made stronger.

  On the other hand, anisotropic or isotropic magnetic powder is applicable as the magnetic powder in the molten compound. For example, examples of anisotropic magnetic powder include ferrite, SmCo, NdFeB, and SmFeN. Considering the magnetic force, anisotropic rare earth magnetic powder is particularly preferable. In consideration of moldability, the SmFeN system is more preferable. Furthermore, examples of the isotropic magnetic powder include SmCo and NdFeB. When it is necessary to produce a bonded magnet having a strong magnetic force, it is preferable to use anisotropic rare earth magnetic powder. This is because anisotropic magnetic powder is very easily aligned in magnetization direction by a magnetic field applied during orientation, and as a result, the magnetic force of the bond magnet is increased. Said magnetic powder can be used individually by 1 type or in mixture of 2 or more types. Moreover, you may perform an oxidation-resistant process and a coupling process as needed.

  Moreover, there is no restriction | limiting in particular as resin which comprises a compound, For example, thermoplastic resins, such as polypropylene, polyethylene, polyvinyl chloride, polyester, polyamide, polycarbonate, polyphenylene sulfide, an acrylic resin, thermoplasticity, such as ester type and polyamide type Thermosetting resins such as elastomers, epoxy resins and phenol resins can be used. Moreover, these can also be mixed and used suitably.

  Furthermore, although the blending ratio of the magnetic powder depends on the type of resin, the ratio of the magnetic powder to the entire bonded magnet is preferably 45 to 75% by volume. Further, an antioxidant, a lubricant and the like can be further mixed.

  By using the magnet for orientation and raw materials as described above, a columnar bond magnet is formed by, for example, a mold shown in FIG.

  Further, by arranging the center pin 111 inside the mold shown in FIG. 1 as shown in FIG. 3, a cylindrical bond in which a through hole is formed in the axial direction of the bond magnet instead of the columnar bond magnet. A magnet can be produced. Here, the center pin 111 is a member that is arranged in a mold in order to form the molten compound into a cylindrical shape. In the cross-sectional view of the mold shown in FIG. 3, the permanent magnet for orientation arranged in the mold is the same as that shown in FIG. In FIG. 3, the anisotropic magnetic powder in the molten compound injected from the gate 106 is filled into the cavity 105 and formed into a cylindrical shape. In addition, although the molded product of a cylindrical bond magnet is demonstrated here, this invention is not limited to a cylindrical bond magnet, Other shapes of cylinders, for example, a cross section is circular, an ellipse, a triangle, It can also be a shape such as a square or other polygons.

  FIG. 4 shows a schematic perspective view of a cylindrical bonded magnet manufactured with the mold of FIG. As shown in this figure, the cylindrical bonded magnet is an alternating multipolar magnet in which N and S poles are alternately generated on the side surface. Further, as shown in FIG. 5, by inserting a core rod into the cavity formed in the central axis direction, an alternate multipolar cylindrical bonded magnet with a core strand is obtained. This core is for improving the strength of the cylindrical bonded magnet, and is not particularly limited as long as its purpose is achieved. It may be a non-magnetic material or a magnetic material. Good. For example, a metal material such as iron or an iron alloy is preferable. In addition, a cemented carbide obtained by sintering tungsten carbide with a binder such as cobalt can also be used as a material for cores other than iron. Furthermore, ceramics may be used as the core material other than the metal material.

  The cylindrical bonded magnet with a core core has a sufficient strength because the core core is penetrated in the central axis direction. Moreover, since the outer peripheral surface of the bonded magnet is not covered with the pipe as in the prior art, an alternating multipolar magnet having excellent magnetic properties can be obtained as compared with that inserted into the pipe.

Examples according to the present invention will be described in detail below. Needless to say, the present invention is not limited to the following examples.
[Example]
1. Compound preparation

Anisotropic SmFeN magnetic powder is surface-treated with ethyl silicate and a silane coupling agent. The surface-treated SmFeN magnetic powder 9137g and 12 nylon 863g are mixed with a mixer. The obtained mixed powder is kneaded at 220 ° C. using a kneader, the strand-like compound is extruded, cooled, and then cut into an appropriate size to obtain a compound.
2. Fabrication of cylindrical and cylindrical alternating multipolar bonded magnets

The compound produced above is used as a raw material, and cylindrical and columnar alternating multipolar bonded magnets are produced with an injection molding machine. As shown in FIG. 3, the molds used in the respective examples have permanent magnets for orientation arranged therein, as shown in Table 1. The cavity has a diameter of 5 mm and a height of 30 mm. In Examples 1 to 3 and Comparative Example 1, the mold shown in FIG. 3 is used, and a center pin 111 is disposed at the axial center of the cavity, and a cylindrical shape is provided with a through hole in the central axis direction. A bonded magnet can be obtained. Here, by changing the diameter of the center pin 111, a cylindrical bonded magnet having different inner diameters (1 mm, 2 mm, 3 mm, 4 mm) is obtained. As Comparative Examples 2 to 3, a cylindrical bond magnet having no through hole in the central axis direction was obtained using the mold shown in FIG.
3. Magnetization treatment

Using the magnetized coil shown in FIG. 8, the cylindrical and columnar bonded magnets obtained above are magnetized. The magnetizing condition in this embodiment is pulse magnetizing with a capacitance of 500 μF and a charging voltage of 1500V. As shown in FIG. 8, the magnetized coil in this embodiment is a coated copper wire that is wound first at a predetermined interval after the coated copper wire 110 is wound around the side surface of the non-magnetic bobbin 109. Is formed by winding in the opposite direction.
4). Evaluation

  As shown in Table 1, cores (material: nonmagnetic steel HPM75) are inserted in Examples 1 to 3 and Comparative Example 1, and Comparative Example 3 has an inner diameter of 5 mm, a wall thickness of 0.2 mm, and a length. Insert into 30 mm SUS304 pipe. Comparative Example 2 is evaluated with the bare magnet remaining without being inserted into the pipe. The surface magnetic flux density distribution in the longitudinal direction of the side surfaces was measured for all the bonded magnets obtained in each of the examples and comparative examples, and the maximum surface magnetic flux density value at this time is shown in Table 1. Further, FIG. 7 is a graph in which the percentage of the inner diameter with respect to the outer diameter of the cylindrical bonded magnet is plotted on the horizontal axis and the maximum surface magnetic flux density on the side surface is plotted on the vertical axis. According to this graph, it can be seen that excellent magnetic properties are obtained when the inner diameter of the cylindrical bonded magnet is 65% or less of the outer diameter. On the other hand, as in Comparative Example 1, when the inner diameter for inserting the core is larger than 65% of the outer diameter, a rapid decrease in the surface magnetic flux density is observed.

  A bending strength test is performed on all products. The strengths of the bonded magnets produced under a stress of 100 MPa were compared based on the presence or absence of cracks and chips of the bonded magnets, and the results are shown in Table 1. In Table 1, “x” is indicated for products with cracks and chipped, and “◯” is indicated for products without cracks. As is apparent from this table, Examples 1 to 3 and Comparative Examples 1 and 3 are superior to Comparative Example 2 because the core wire is inserted in the center or the bonded magnet is inserted into the pipe. Has strength.

  From the above results, it is possible to insert cylindrical core magnets into the center of a cylindrical bonded magnet having a hole whose inner diameter is within 65% of the outer diameter. It became clear that a pole bonded magnet could be realized. Moreover, sufficient strength and excellent magnetic properties could be obtained by using a cylindrical bonded magnet having a hole with an inner diameter in the range of 10% to 65% of the outer diameter. Furthermore, it is preferable to use a cylindrical bonded magnet having a hole with an inner diameter in the range of 10% to 50% of the outer diameter in terms of obtaining excellent magnetic properties.

  In the above example, the center pin is disposed at the axial center of the cavity to obtain a bonded magnet, and then the core is inserted. However, the present invention is not limited to this configuration. For example, a center pin is not used at the time of molding a mold, and the core is itself placed at the center of the cavity and the core is fixed in the center of the bond magnet. It goes without saying that it is also possible to do.

  The cylindrical bonded magnet of the present invention can be used as a permanent magnet material for a foreign substance removing device or a linear motor.

101, 101a, 101b, 102, 102a, 102b ... orientation magnet 103 ... ejector pin 104 ... molding die 105 ... cavity 106 ... gate 107 ... cylindrical magnet 108 ... core 109 ... bobbin 110 ... coated copper wire 111 ... Center pin

Claims (4)

A cylindrical bond magnet formed of magnetic powder and resin, with a hollow through hole opened inside,
The cylindrical bonded magnet is a molded body that is integrally molded,
In the axial direction of the through-hole, at least four or more N poles and S poles are alternately magnetized.
The cylindrical bonded magnet is characterized in that the inner diameter of the cylindrical bonded magnet is in the range of 10% to 65% of the outer diameter. The cylindrical bonded magnet according to claim 1, further comprising:
The cylindrical bonded magnet according to claim 1, further comprising a core rod inserted into the through hole and having an outer diameter substantially the same as an inner diameter. The cylindrical bonded magnet according to claim 2,
The cylindrical bonded magnet is characterized in that the magnetic powder constituting the cylindrical bonded magnet is an anisotropic rare earth alloy powder. Kneading magnetic powder and resin to obtain a compound;
Forming the compound into a cylindrical bonded magnet under an environment in which an orientation magnetic field is applied;
A method for producing a cylindrical bonded magnet including:
The orientation magnetic field is formed by an orientation magnet in which a plurality of permanent magnets are joined so that the same kind of magnetic poles face each other.
The method for producing a cylindrical bonded magnet, wherein the orientation magnet is arranged so as to surround the cylindrical bonded magnet.

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